1. Field of the Invention
This invention relates to an apparatus for evacuating a bottle, vessel or container and has particular, but not sole, utility in the medical field.
2. Cross References to Related Applications
My U.K. patent application No. 85.14616, which corresponds to U.S. patent application Ser. No. 872,042 filed June 6, 1986, which describes a sealing cap for a bottle, vessel or container, which cap includes a valving arrangement permitting the container to be evacuated prior to use, and is then self-sealing. The cap incorporates a plug which is initially in a first position, sealing the cap. For evacuating the container, the plug is pushed inwards to a second position, in which there is a clearance around the plug to allow air to be withdrawn under suction from the container. Finally, immediately after the evacuation, the plug must be pushed inwards to a third position, in which it seals the cap and this seal is assisted by the plug being urged against its seat under the influence of the evacuation in the container. A bottle or other container, fitted with such a cap, may be used for collecting a sample of blood, in which case the cap is arranged to be pierced by a fine tube or needle so as to apply suction through that tube, from within the container, and thus draw a sample of blood into the container. By evacuating the container immediately prior to its use, it can be ensured that there is a predetemined level of vacuum within it and that the vacuum has not dissipated with time.